1. Field of the Invention
The present invention relates to touch control devices and, particularly, to a carbon nanotube based touch control device.
2. Discussion of Related Art
Following the advancement in recent years of electronic technology, more and more electronic apparatuses (e.g., Global Position Systems, video and audio devices, mobile phones, and air conditions) are added in vehicles, especially in cars. However, control devices of the apparatuses are commonly disposed on a front panel of the car together with drive-control devices in a limited area and not convenient for using. Therefore, to solve the above-mentioned problem, a touch control device that includes a touch panel and a display device set on an inner surface of a windshield of the car has been developed.
Different types of touch panels that will be used in the touch control device, including resistance, capacitance, infrared, and surface sound-wave types, have been developed. Due to their high accuracy and low-cost of production thereof, the resistance-type touch panels have been widely used.
A conventional resistance-type touch panel includes an upper substrate, a lower substrate, and a plurality of dot spacers. The upper substrate includes an optically transparent upper conductive layer formed on a lower surface thereof, and two upper electrodes connected to the optically transparent upper conductive layer at two edges along the X direction respectively. The lower substrate includes an optically transparent lower conductive layer formed on an upper surface thereof, and two lower electrodes connected to the optically transparent upper conductive layer at two edges along the Y direction respectively. The plurality of dot spacers is formed between the optically transparent upper conductive layer and the optically transparent lower conductive layer. The upper substrate is a transparent and flexible film/plate. The lower substrate is a transparent and rigid plate made of glass. The optically transparent upper conductive layer and the optically transparent lower conductive layer are formed of conductive indium tin oxide (ITO). The upper and lower electrodes are formed by layers of silver paste.
In operation, an upper surface of the upper substrate is pressed with a finger, a pen or the like tool, and visual observation of a screen on the display device provided on a back side of the touch panel is allowed. This causes the upper substrate to be deformed, and the upper conductive layer thus comes in contact with the lower conductive layer at the position where pressing occurs. Voltages are applied successively from an electronic circuit to the optically transparent upper conductive layer and the optically transparent lower conductive layer. Thus, the deformed position can be detected by the electronic circuit.
However, the ITO layer generally has poor mechanical durability, low chemical endurance, and uneven resistance over an entire area of the touch panel. Moreover, the ITO layer has relatively low transparency in a humid environment. As such, the conventional touch panel is unsuitable for use in a car, especially when driving in the rain or snow. All the above-mentioned problems of the ITO layer tend to yield a touch panel with somewhat low sensitivity, accuracy, and brightness. Furthermore, the ITO layer is generally formed by means of ion-beam sputtering, and this method is relatively complicated.
What is needed, therefore, is to provide a touch control device having good durability, high sensitivity, accuracy, and brightness.